Experiences and Hopes Among Patients with Colorectal Carcinoma and Peritoneal Metastases Who Are Participating in an Early-Phase Clinical Trial

<i>Background:</i> Radspherin^® is a novel α-emitting radiopharmaceutical administered intraperitoneally following complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for peritoneal metastases. It delivers short-range radiation aimed at eliminating residual microscopic disease. This qualitative study explored how participants with colorectal cancer experienced participating in an early-phase clinical trial involving CRS-HIPEC followed by Radspherin^®. <i>Materials and Methods:</i> Semi-structured interviews were conducted with ten participants enrolled in a phase 1/2a trial involving CRS-HIPEC and intraperitoneal Radspherin^®. The analysis was guided by a phenomenological and interpretive approach using reflexive thematic analysis. <i>Results:</i> Participants expressed a strong sense of motivation and hope tied specifically to receiving Radspherin^®, which they perceived as an opportunity to improve their prognosis. Many also viewed participation as a contribution to future cancer research. None attributed complications or side effects to Radspherin^®. Clear and supportive verbal communication from healthcare professionals was highly valued, while the written information was described as overwhelming. Despite fears of recurrence, most participants remained optimistic about regaining a meaningful life. While experiences with Radspherin^® were largely positive, participants also described pain, fatigue, and prolonged recovery related to CRS-HIPEC, including ongoing functional and psychosocial challenges. <i>Conclusions:</i> Participants associated Radspherin^® with hope and a therapeutic benefit but did not link it to their adverse events. Their willingness to participate in experimental treatment was shaped by trust in clinicians, clear communication, and a desire for extended survival. However, the burden of CRS-HIPEC-related side effects underscores the importance of tailored follow-up and support.